PCBS hydrometallurgy technology
hydrometallurgy technology in recovery of valuable metals in the waste circuit board is mainly using the valuable metals in the circuit board can be dissolved in nitric acid and aqua regia, strong oxidizing medium into the characteristics of the liquid phase, make the most of precious metals and other metal into liquid instead of bricks and phase separation, and then recycling all kinds of metal from the liquid phase. Using hydrometallurgy technology the metal in the recycling of waste circuit board, takes apart, choose ( Large pieces of metal, does not contain precious metal parts) , crushing ( After the comminution powder separation for metal and non-metallic) Such as technology, then chemical leaching of precious metals and other valuable metals. Therefore, hydrometallurgy technology can be used as a mechanical and physical method of dealing with the waste circuit board the follow-up process.
the Johnson Matthey electronics co. , LTD. In the late 1970 s began to research using hydrometallurgy technology to extract precious metals from electronic waste, and put forward a tentative recovery process. At the university of Sao Paulo, Brazil, Soares Tenorio etc. On the basis of predecessors' research improvements introduced a leaching process. The process before the leaching method adopting physical sorting out influence other metals, precious metals leaching to simplify subsequent leaching process, the leaching efficiency. In the ( NH4) 2 so4, and NH4Cl In ammonia solution, using Cu ( II) As oxidant leaching copper on the PCB, Cu ( II) The metal copper reduction into Cu ( I) The formation of Cu ( NH3) 2 +, again through the extraction separation of zinc, Pb, Mn and other impurities, then get high purity electrolytic copper.
began to related research in China starts late, but develops fast. Jing-ying li studied such as lime sulfur mixture method leaching waste circuit boards in the gold. In the quality of solid and liquid volume 1:3, concentration of sodium sulfite 0. 1 mol/L, copper sulfate, concentration of 0. 03 mol/L, ammonia concentration of 0. 5 mol/L, reaction time 2. 5 h 40 ℃, reaction temperature, pH = 10 conditions, the gold leaching rate of more than 85%. Wang Zhe by mibk (such as MIBK) Extract the gold in the waste circuit board, through the Plackett - Burman compared experiment design screen, extraction time and extraction temperature as the main influence factors, and the response surface method to optimize the three parameters: the compared, extraction time and extraction temperature is 0, respectively. Do, 9 min, and 20 ℃ condition, the gold extraction rate was 98. 36%. Li yw, such as sulfur vein was studied in computer motherboard cicc leaching process, it is concluded that in sulfuric acid mass fraction 15%, Fe3 + mass concentration of 4. 5 g/L under the condition of leaching 60 min, the gold leaching rate, the largest up to 91. 14%. Xu Qu etc by using iodide leaching gold of PCBS, room temperature, when the mass fraction of iodine is 1. 1% iodine and iodine ion of the amount of substance ratio of 1:10, hydrogen peroxide solution volume fraction of 1. 5%, the leaching time of 4 h, quality of solid liquid volume ratio of 1:10, pH to neutral conditions, the gold leaching rate was 97. 5%.
mechanical physical comprehensive recycling of waste printed circuit board caught the attention of more and more scholars and enterprises, have developed efficient dismantling, grinding, sorting equipment and optimizing the recycling production line. But the mechanical method to get the product is not the final product, need further separation, purification and refining. Hydrometallurgy technology can be used as a subsequent work of mechanical and physical treatment, chemical reagent consumption but hydrometallurgy technology in large, leaching liquid and residue is corrosive and toxic and difficult to recycle all metal, non-metallic problems such as not recycled. From the point of the present research level and depth, adopt 'mechanical and physical separation + hydrometallurgy process back to factory waste circuit board has the advantages of can realize industrialized production in the short term, but the whole process of optimization, and the prevention and control of environmental pollution in the process of production is still the focus of future research.
1, spinning, this paper this net, does not mean this website agree with their views and responsible for its authenticity, textual research.
2, as this article involves the content of his works, copyright and other issues, please contact with this net in 30 days, we will deal with it accordingly in the first time!